Re: [Lse-tech] [RFC] [PATCH] Scalable Statistics Counters

[Anton Blanchard]

Hi,

> > There's several things where per cpu data is useful; low frequency
> > statistics is not one of them in my opinion.
> 
> ...which may be true for 4-ways and even 8-ways but when you get to
> 32-ways and greater, you start seeing cache problems.  That was the
> case on AIX and per-cpu counters was one of the changes that helped
> get the spectacular scalability on Regatta.

I agree there are large areas of improvement to be done wrt cacheline
ping ponging (see my patch in 2.4.17-pre6 for one example), but we
should do our own benchmarking and not look at what AIX has been doing.

Anton
(ppc64 Linux Hacker)